This invention relates to a system for resetting bone-fracture fragments.
A number of devices for the alignment or realignment of the fragments of a fractured bone are known in the art. For example, WO 95/24161 discloses a repositioning device for gradual correction of a bone fracture that has been set in the operating room and is attached to an external fixation device. The disclosed device is limited to acting in three directions and is adjustable only along a single plane. Repositioning of this device involves the following steps:
The repositioning unit is attached to the fixation unit in such manner that the center of rotation of the repositioning unit is lined up with the fracture. The rotational and translational repositioning is performed in a first plane whereupon the joints of the fixation unit are locked in position, stabilizing the fracture.
Next, the screws connecting the repositioning unit and the fixation unit are loosened and the entire repositioning unit is swiveled into a second plane which is preferably perpendicular to the first plane, followed by a retightening of the connecting screws. The joints of the fixation unit are unlocked, the unit is repositioned in the second plane and the joints are again locked in position.
The drawback of this concept lies in the fact that for rotational repositioning around the longitudinal axis of the bone, an articulated parallelogram must be mounted between the fixation unit and the repositioning unit, involving corresponding efforts and complexities.
The following invention is designed to solve the problem. It is based on a concept intended to permit all repositioning steps to be performed quickly and dependably.
The present invention relates to a device for repositioning fragments of a fractured bone. The device includes a first clamping unit attached to the bone by at least one first bone fastener, a second clamping unit attached to the bone by at least one second bone fastener, first, second, and third translation components operatively associated with at least one of the first and second clamping unit for relative translational movement of one clamping unit with respect to the other along a respective first, second, and third translation axis, and first, second, and third rotation components operatively associated with at least one of the first and second clamping unit for relative rotational movement of one clamping unit with respect to the other about a respective first, second, and third rotation axis.
Preferably, each of the translation and rotation components can be operated independently of the others. In one embodiment, the first, second, and third translation axes form an oblique-angle coordinate system.
The device can also include first and second parallel rod sections. The first and second clamping units each comprises a clamping jaw for receiving the bone fasteners and a connecting jaw connecting the clamping jaw to the first and second rod sections. The first rod section connects the first clamping unit to the first rotation component, and the first rotation component comprises a curved bar member, with the first rod section movable along the curved bar member while still maintaining a parallel relationship between the first and second rod sections. Preferably, the curved bar member has a radius of about 50 to 200 mm. The second rod section connects the second clamping unit to the second rotation component and operation of the second rotation component pivots the second rod section about the second rotation axis. The second and third translation components and the third rotation component are each connected to the first rod section. Additionally, the second rotation component engages the third rotation component to connect the first and second clamping units.
The first rotation component preferably has a receiving component having a channel for slidably receiving the curved bar member and an adjustment mechanism for causing movement of the curved bar member relative to the receiving component. The first translation component preferably comprises a tubular cylinder configured for slidably receiving a first end of the first rod section and an adjustment mechanism for causing relative movement of the first rod section and tubular cylinder.
The second and third translation components each preferably comprises a first block having a slotted track and fixed to the third translation component, a second block, at least a portion of which is slidably received in the slotted track, and a drive for causing relative movement between the first and second blocks. The second and third rotation components each preferably comprises a mount having a U-shaped slot at one end, a pivoting element, at least a portion of which is received in the slot, a pin pivotably coupling the mount and the pivoting element; and a drive for causing pivoting of the pivoting element with respect to the mount.
Its advantage is based on the ability to permit repositioning around the longitudinal axis of the bone by means of a progressively rotatable segmental arch, a concept which eliminates time-consuming setup operations.
The chief benefits of this invention are offered by the fact that the system according to this invention permits rapid resetting of the bone fragments without the complicated flip-over into two different planes (an iterative process in prior art).